Wireless networks may provide packet-based services to wireless communication devices (WCDs). For example, a radio access network (RAN) may define one or more wireless coverage areas through which the WCDs may obtain wireless communication services from the RAN. A particular WCD may communicate with the RAN via one or more of the RAN's base stations. In order to make this communication more efficient, for example, the RAN may assign one or more pairs of uplink and downlink channels to the WCD. However, the quality of communications via the assigned channels' carrier frequencies may change over time.